THE ASTRAGALUS. 233 
 (Faweett, Hd. Med. Journ., 1895). Over the external border the cartilage-covered 
surface is continuous externally with an extensive area of the form of a quadrant. 
This is concave from above downwards, and articulates with the inner surface of the 
fibular malleolus. Its inferior angle is prominent and somewhat everted, and some- 
times referred to as the 
external process (pro- 
cessus lateralis tal). 
The inner aspect of the 
body has a comma- 
shaped facet, confluent 
with the superior 
articular surface, over 
the inner edge of the 
trochlea; this articu- 
lates with the outer 
surface of the tibial 
malleolus. Inferior to 
this the bone is rough 
Tendo Achillis 
Plantaris 
SOs iCALCIS 
— ASTRAGALUS 
and pitted by numerous i digitorum ——V 
small openings, and \ 
J ust below the tail of CUBOID d ee Navicdva R 
the comma there is a 
circular impression for Peroneus brevis 
the attachment of the 
— pact 
_ MIDDLE 
mS 
CUNEIFORM 
deep fibres of the inter- Tea 
nal lateral ligament. 
On the inferior surface Peroneus 
tertius Sane 
~ Tibialus 
_ there is a deep concave 
facet, called the  pos- 
terior calcanean facet Dorsal 
(faciés caleanea articu- ee 
laris posterior), which V. Merararsat 
is of more or less oval 
or oblong form and is 
placed obliquely from 
behind forwards and 
outwards; this rests 
_- anticus 
I. METATARSAL 
a 
4 upon a corresponding interac wf i ! ‘a (A Cus SESAMOID BONE 
% = anc \\ f 
Burtace. jon; the upper trices 
aspect of the os calcis. 
In front of this, and 
crossing the bone from 
within outwards and 
forwards, isa deep furrow 
(sulcus tali), the floor of oes He 
which is pierced by © digitoram™ 
numerous large canals. 
It serves for the attach- 
ment of the strong in- 
terosseous ligament 
which unites the astra- 
: galus with the os calcis, THIRD OR TERMINAL PHALANX 
and separates the facet 
already described from 
a smaller oval articular surface having a slightly convex surface, which lies im- 
‘mediately in front of it. This is called the middle calcanean facet (facies articu- 
laris calcanea media), and articulates with the upper surface of the sustentaculum 
tali of the os calcis. Posteriorly the body is provided with two tubercles, separated 
_by a groove; the external of these (processus posterior tali) is usually the larger 
Extensor 
brevis 
digitorum 
Extensor 
proprius 
hallueis 
\ pall j 
SEY PHALANX &\ig 
Fia. 173.—BONES OF THE RIGHT FOOT AS SEEN FROM ABOVE. 
